The 4C's

The 4Cs of diamonds (cut, colour, clarity, and carat weight) were created by the Gemological Institute of America (GIA) in the 1950s as a standard to grade diamonds. They also established the scientific methods and procedures for objectively grading a diamond’s quality. The establishment of the Diamond 4Cs and the GIA International Diamond Grading System™ signified two major implications: diamond quality could be expressed in a universal language allowing buyers and sellers to easily understand a diamond’s value.

The 4C’s is the universal method that is still used for assessing the quality of any diamond, anywhere in the world. 

To make an educated decision when purchasing a diamond, you need to determine which of the 4C's is most important to you. This will allow you to narrow your options so you can make the best choice for your budget. The Calico team would love to discuss these factors with you and help you understand which factors will give you the best value.

When referring to “cut,” people often think of the shape of a diamond rather than its cut quality. The shape of a diamond is the outline of the diamond when viewed from the top. 

The “Cut” of a diamond indicates the quality of that diamond’s proportions, polish, and symmetry.  These factors will affect how much brilliance and sparkle (or scintillation) the diamond will have. The Cut Scale of Diamonds is used to determine the quality. 

The Cut Scale of Diamonds is divided into five categories: Excellent, Very Good, Good, Fair, and Poor. An Excellent cut diamond has the most brilliance and sparkle, and it reflects most of the white light that enters it. A Very Good cut diamond is still quite brilliant, but slightly less so than an Excellent cut. So on and so forth until the categorization of Poor cut. This diamond reflects very little light, and may appear dull, cloudy, and lifeless.

To note, diamonds with perfect clarity or colour may seem desirable, however, if they are poorly cut, they will appear dull and lifeless. On the other hand, even diamonds with average or below average colour and clarity can appear brilliant if they have an excellent cut.

When buying a diamond, it is important to consider the Cut Scale. A higher cut grade means a more brilliant diamond, and a better value. However, it is important to remember that the Cut Scale is only one of the four Cs of diamond buying (the others being Clarity, Colour, and Carat.)If the Cut, polish and symmetry are graded as Excellent, this is what is referred to a triple excellent, and are quite rare. 


The “Clarity” of a diamond indicates how free that diamond is of inclusions and blemishes, or other imperfections, that may affect its beauty and durability. Because diamonds are formed under extreme heat and pressure, deep within the earth, they often contain unique birthmarks either internal (inclusions) or external (blemishes). While creating lab-grown diamonds these birthmarks can occur as they follow the same natural processes. Diamonds without birthmarks are rare, and this rarity will impact a diamond’s value. Every diamond is unique whether earth mined, or lab created.


To determining a clarity grade, the diamond grader will consider the size, nature, position, colour and quantity of clarity characteristics visible under 10X magnification. The Clarity Scale contains 11 grades ranging from flawless (FL) to included (I3), with the majority of diamonds falling into the VS (very slightly included) or SI (slightly included) categories. No diamond is perfect although some come close. These are classified as Flawless diamonds and are exceptionally rare.


The “colour” of a diamond is about what you can’t see rather than what you can see. A diamond’s value is related to how closely it approaches being colourless. The less colour visible in a diamond equates to a higher value. The exceptions are fancy coloured diamonds (LINK TO FANCY COLOURED DAIMOND EDUCATION PAGE) which lie outside this colour range.


Diamond colour is graded on a scale from D to Z, with D being colourless and Z having a heavy yellow hue. Diamonds beyond Z are called "fancy" and have their own grading system. The more intense and pure the colour, the more valuable the diamond is because of its rarity.


Diamonds are colour-graded by comparing them to master stones of true colour grades identified under controlled lighting and precise viewing conditions. Many of these colour distinctions are so subtle between grades as to be unobserved to the untrained eye. But these slight differences make a substantial difference in diamond quality and price.  

Carat (Weight)

“Carat” is a unit of measurement used to measure the weight of diamonds and other gemstones. One carat is equal to 0.2 grams. For reference that is about the same weight as a small paperclip. One carat is divided into 100 points, similar to how a dollar is divided into 100 pennies. For example, 50-point diamond weighs 0.50 carats. In the diamond industry, weight is often measured to the hundred thousandths of a carat and rounded to a hundredth of a carat. Diamond weights greater than one carat are expressed in carats and decimals. (For instance, a 1.08 ct. stone would be described as “one point oh eight carats,” or “one oh eight.”)

  *Note that there is a difference between Carat and Karat.